Electric switch



M. W. GRIFFES ELECTRIC SWITCH July 18, 1950 4 Sheets-Sheet l Filed Oct.16. 1946 July 18, 1950 M. w. GRIFFEs 2,5l5,596

ELECTRIC SWITCH Filed o=. 16, 1948 4 SheetS-Sheet 2 INVENTOR. M11. razvW 'R/FFEJ /477'0 mw: YJ

July 18, 1950 M. w. GRIFFEs 2,5l5,596

ELECTRIC SWITCH 4 Sheets-Sheet 3 Filed Oct. 16, 1946 43 AffaAM/EVJ M. W.GRIFFES July 18, 1950 ELECTRIC SWITCH 4 Sheets-Sheet 4 Filed Oct. 16,1946 INVENTOR.

M/L TON M GR/FFS BY Y M1) W TTORIYEY'S.

Patented July 18, 1950 ELECTRIC SWITCH Milton W. Grifl'es, Cleveland,Ohio,

asaignor to 'l'lle Electric Controller & Manufacturing Company,Cleveland, Ohio, a corporation of Ohio Application October 16, 1946,Serial No. 703,502 Claims. (Cl. 200-147) This invention relates toelectrical current interrupters or switches. and more particularly to anelectrical switch especially designed for interrupting altematingcurrents of power magnitudes and of relatively high frequency but usablealso for interrupting alternating eurrents of the usual powerfrequeneies and direct currents as well.

Some form of magnetic blowout structure is almost universally used toassist in extinguishing the are or ares formed when an air-break switchopens a circuit carrying a current having a magnitude within the rangecommonly used by industrial apparatus, and, in the case of switches ofthe electro-magnetic contactor type, the blowout structure generallyincludes a blowout coil which is connected permanently in series withthe stationary contact of the contactor so that all of the currentflowing through the contacts while the contacts are closed also flowsthrough the-blowout coil. No particular difiieulty is involved in thedesign of a permanently connected blowout structure that neither offersappreciable impedance nor heats -unduly when the switch carries-currents of the magnitudes commonly used by industrial apparatus and ofa frequency in the neighborhood of 60 cycles, per second, but if thefrequency of such currents is in the range of from say 200 to 10,000cycles per second or higher, the impedance of the blowout coil and theheating thereof and of its associated iron structure is such that usualblowout practice cannot be followed. Consequently, conventionalair-break, electro-magnetic contactor type switches which havepermanently connected blowout coils and which are designed forinterrupting alternating currents of the standard power frequencies, i.e. 25 or 60 cycles per second, are not suitable for interruptingalternating currents of the large magnitude and high frequency nowcommonly used, for example, to supply eoreless type induction furnacesor heaters.

Electromagnetic contactors for industrial control service and havingcontinuous 230 volt ratings of the order of 1200 amperes or less atstandard power frequencies have become very highly developed andstandardized so that it is desirable to adapt such contactors forservice in comparable power ranges at frequencies of from 2000 to 10,000cycles per second thereby to make them suitable for controllingInduction heaters. Previous attempts to accomplish this result haveinvolved the use of a means which short circuits the blowout coil duringthe closed period of the eontactor and which is operable shortly beforeopeningof the main switch contacts to remove the short circuit therebyto render the blowout coil effective to assist in are extinguishment. Insome instances the short-circuiting means is one pole of a triple-polecontactor and is connected in multiple with the blowout coi1 and thecontacts of one of the other poles, the parallel combination beingconnected in one of the line conductors. The remaining pole, like theshort circuiting pole, is not provided with ablowout coil and isinterposed in the other line conductor. During circuit opening operationof such a contactor, the short circuiting pole opens first to insert theblowout coil into the circuit; the pole having the blowout coil thenopens and the are is extinguished, and then the remaining pole opens tocompletely isolate the two parts of the circuit.

Another prior contactor type switch designed for high frequency serviceinvolves' the use of additional or areing contacts connected in paral-Iel with the main contacts of the switch and m series with the blowoutcoil so that the main contacts short circuit the blowout coil when theyare closed. The main contacts of this latter type of prior contactor arearranged to open shortly before the arcing eontacts open thereby tocause the blowout coil to become energized just before and to remainenergized during the areing period, the arc appearing across the arcingcontacts only.

Both of the foregoing prior attempts to solve the problem of highfrequency are interruption by modified standard low frequency contactorshave required considerable redesign of the standard low frequencycontactors, and have necessitated a predetermined sequence of contactopening which is difilcult to maintain. In both instances it has beennecessary to derate the modified contactors considerably when used forhigh frequency service, and, in the case of the first described priorhigh frequency contactor, difliculty has been experienced because thelast pole sometimes opens before the arc formed at the intermediate poleis completely extinguished thereby causing an are to be formed oncontacts which are not in a blowout field.

An object of this invention is to provide an improved electro-magneticswitch capable of interrupting relatively large currents of relativelyhigh frequency.

Another object is to provide an electro-magnetic switch for interruptinghigh frequency currents and which does not have the foregoingdisadvantages.

atiaeoe Another object is to provide a switch for interrupting highfrequency eurrents and which is essentially similar to commereiallyavailable contactors in so far as the prineipal-structural features areconcerned.

While the improved eontaetor disclosed herein may be eonstrncted byslight modification of many eontactors now available commercially, theeontaetor disclosed in Trofimov Patent No. 2,071,595, issued February23, 1937, is particularly well suited for this purpose and is thegeneral type shown in the exemplary embodiments herein deseribed.

In aecordance with the present'invention, the blowout coil of aeontaetor type switch is so connected that it is completely isolatedfrom the circuit while the main eontacts of the switch are closed, andis introduced for the first time into the circuit after an are is formedand has been transferred by thermal forces from one of the contaets toan are terminal receiving means in the form of an arcing plate. Theareing plate is eleetrically connected to the movable contact throughthe blowout coil and through a pair of parallel connected arecontrolling conductors which are connected in series with the blowouteoil and disposed on opposite sides of the are path. The are controllingconductors not only serve as a path for current flowing through theblowout coil, but also are so mounted with respect to the are path thatthe current fiowing in the conductors tends to confine the are to aplane midway between the are shields, as in the above mentioned Trofimovpatent. The blowout structure is so designed that the impedanee of theeoil is a minimum thereby to facilitate are transfer, but forinterrupting currents having frequencies in the neighborhood of 10,000cycles per second or whenever the are does not transfer readily from themoving contact to the arcing plate due to the thermal effect of the areitself, auxiliary means are provided to assist such transfer.

Switehes are known in which additional blowout eoils are added to acircuit in response to movement of an are across an areing surface, andin which the energization of a blowout eoil is inereased from a low to ahigh value consequent upon transfer of an are from a movable contact toa stationary arcing plate. However, these prior switehes are notsuitable for high frequency service since they are provided with highlyinductive magnetic means for effeeting initial are transfer and theimpedanee of the blowout coils is made as great as possible so as toassist in reducing the are current. When the impedanee of the blowoutcoil is relatively large, some means must be used to assist the thermaleffect in order to move the are to the stationary plate, and when thismeans is the usual blowout structure, the switch cannot be used for highfrequency services. The present applieant has discovered that if theimpedanee of the blowout coiI is kept as low as possible and the arcingplate is properly positioned' relative to the path of movement of themovable switch contact, that ares having a frequency as high as 6000 to8000 cycles per second can be caused to move to the areing plate withoutthe use of an auxiliary means.

It is a further object of this invention to provide a blowout structurefor high frequency are interruption that is initially energizedeonsequent upon transfer of the are from a contact to an arcing surface.

surface by the force of repulsion between the current in the are 'andthe currentin an adjacent conductor.

Still another object is to provide an are eontrolling structure for anelectric switch including means utllizing the force of repulsion betweenoppositely flowing eurrents in adjacent conducting paths to expand anare and to confine the are laterally to a pre-determined path andfurther including magnetic blowout means effective only after initialexpansion of the are to assist in further expansion and ultimateextinction of the are.

Still another object is to provide an are controlling structure for anelectric switch including means utilizing, the 'force of repulsionbetween oppositely flowing eurrents in adj acent corrdueting paths tomove an are into a position in which it initiates energization of ablowout eoil by which the are itself is subsequently extinguished.

A more specific object is to so arrange the usuai fiexible conductormeans leading to the movable contact of a clapper-type electromagnetiecontactor that the current flowing through the fiexible conductor meansserves to repel and expand an are immediately after its formationbetween the eontaetor eontacts.

Other objects are to provide a switch having a blowout coii of minimumimpedanee that is energized only after an are is formed; to provide aswitch having means in addition to a magnetic blowout structure forexpanding an are, and to provide a switch having air-blast means fortransferring an are from a movable switch contact to a stationary arcingsurface.

Other objects and advantages will become apparent from the followingdescription wherein reference is made to the drawings, in which:

Fig. l is a circuit diagram;

Flg. 2 is a side elevation of a magnetic contactor in accordanee withthis invention;

Fig. 3 is a front elevation of the eontaetor of Fig. 2,=portions of the'structure, at the left, being broken away;

Fig. 3a is a detail sectional plan view taken as indicated at 3a-3a onFig. 2;

Fig. 4 is a perspective Vview of the eontaetor of Fig. 2 Vwith the airblast mechanism removed and the movable parts dropped to an abnormallyopen position;

Fig. 5 is a sectional view taken generally at 5-5 on Fig. 3, and

Fig. 6 is a detail view of an air blast generating mechanism of theswitch.

Fig. 7 is a fragmentary side elevation of a eontaetor generally such asillustrated in Fig. 2, showing a modification of the invention.

Briefiy stated, the form of the present invention shown in the drawingseomprises an insulating base E0 mounting two identical pole structures Hand i (Figs. 3 and 4) each of which has a pair of complemental contactslt and i5 adapted to engage each other to complete a suitable electricalcircuit therebetween. As shown in Fig. 1 by way of example, such asuitable circuit may c`omprise, for each of the pairs of contacts M and|5, a supply conductor lt extending from a source of altemating currentG to an induction furnace F.V

Since the poles ll and l2 are identical and like see Fig. 2, flowsthrough parts are referred to by the same reference numerals, thefollowing will sufllce for both. Directly above the open contact i ispositioned an arc terminal receiving means or arc-dissipating plate |8having an inner end portion 18a (Figs. 1 and 5) of its lower or bottomface in close proximity to the vpath of travel of the top edge of thecontact |5, while connected to and extending upwardly and rearwardlyfrom the contact |4 is a generally inverted U-shaped conducting guard orarc-dissipating member IB. Between the front and rear walls of themember I!! is an arc-expanding means in the form of a blowout coil 20, alaminated, highly permeable core 2| of magnetic material surrounded bythe coil, and a pair of laminated ear portions 22 of the core and oflike magnetic material in magnetic flux conducting engagement with thecore and extending toward and disposed on opposite sides respectively ofthe contacts |4 and |5. One terminal lead 24 of the blowout coil isconnected to a lower terminal block 25 to which the contact 15 is alsoelectrically connected as by a fiexible conductor 2G and a rocker arm28. The other terminal lead 29 of the blowout coil is connected to aconducting U-shaped bracket 30 (see Fig. 3a) secured to the base IO andpivotally mounting, as on a pin 30a, a pair of conducting plates 3| towhich the inner ends of a pair of conductors 32 are respectivelyconnected. The conductors 32 constitute arcconstraining means as willhereinafter be described. The plates 3| are rigidly fastened as by abolt dla to complemental arc shield members 34 of insulating materialdisposed on opposite sides of the contacts 14 and |5. The members 34support the respective conductors 32 on curved ledge surfaces 34a formedon the outer surfaces of the respective members 34. The outer ends ofthe conductors 32 are connected to the plate [8, and, since the members34 are disposed on opposite sides of the arc path, the conductors 32 arelike- Wise so disposed. The contact l4 is mounted on the outer endportion of a conducting bracket 35 secured to the base |0 by a threadedstud 36 which is electrically connected, as by a bus bar 38, to an upperterminal block 39. The .arcdissipating member |9 which is also mountedupon the bracket 35 has its inner end insulated therefrom as by a fiberspacer |9a in order to prevent the completion of a short circuited turnabout the blowout coil 20.

When the contacts |4 and |5 are in mutual contact, current reaching theswitch through a conductor`31 and a lug 31a at the terminal 39, the busbar 38, the stud 36, the bracket 35, the contacts l4 and l5, the arm 28,and the conductor 26 to the terminal 25 to which an outgoing conductor43 is connected by means of a lug 43a. The blowout coil 20 is thuscompletely isolated and no heating of the coil 20, core 2 I, and/or ears22 results even though the switch is carrying currents of relativelyhigh frequency. When an arc is formed as at (Fig. 5) upon separation ofthe contacts |4 and 1,5, the

passes the irmer edge portion 18a of the plate |8 (broken line positionl5x) one end of the arc transfers from the contact |5 to the plate 'IBas indicated at 42. It should be observed that the transfer of the arcmay be obtained merely as a result of the thermal effects thereof andthat the transfer is facilitated by the close proxdescription of onepole imity of the contact |5 and plate 18. Upon transfer of one end ofthe arc to the plate IB. the flow of current through the contactor isfrom the terminal 39 to the contact I 4, as before, and from the contactl4 through the arc to the plate 18, through the spaced arc-constrainingconductors 32 in parallel, the plates 3|, the bracket 30, the lead 29,the blowout coil 20, and the lead 24 to the terminal 35. The blowoutcoil 20 is so wound that the magnetic field created thereby between theears 22 in Vconjunction with the thermal effect of the arc itself causesth: arc to expand upwardly and outwardly away from the point of itsinception as indicated at 44 and 4'5. In some instances it may bedesirable to raise the respective outer end portions of the blowout ears22 slightly from the position shown in order to concentrate the fluxmore closely to the arc during its period of expansion.

During expansion of the arc, one end thereof moves forwardly along theplate IB whereas the other end of the arc moves upwardly and rear-Wardlyalong the member IS. As described more in detail in the abovementioned Trofimov patent. the effect of the current flowing in theconductors 32 which, in the present invention, are energized as soon asthe arc transfers from the contact |5 to the plate IB, is to constrainthe arc to a position centrally of the spaced arc Shield members 34 andthus to confine the arc in the strongest part of the blowout fieldbetween the ears 22 as well as to prevent the arc from contacting andburning the arc shields.

In event that the contactor is to be used for currents of frequencies inthe neighborhood of 10,000

48 through suitable tubes 5|. The nozzle is mounted beneath the contactHi and the jet orifices 49 are directed into the arc path, i. e.upwardly and across the forward face of the contact S4.

Transfer of the arc from a movable contact to an arcing plate may alsobe effected i the force of repulsion between two adJacent curfiowing inopposite directions as will be described'hereinafter in connection withFlg. 7.

Having thus briefiy described the salient features of the invention,attention is now directe'd to the general construction and arrangementof the contactor hereof.

A cylindrical Operating shaft 54 rot'atably supported by a pair ofspaced brackets 55 mounted by the panel IO has squared insulating tubes56 disposed over opposite end portions thereof. Main contact arms 58 ofthe poles ll and 12, respectively, are secured to the outer end portionsof the respective tubes 58 and a magnet arm 59 has opposing leg portions59a (Fig. 3) secured to the inner end portions of the respective tubes56. Considering one of the identical poles H and 12, the arm 58 thereofjournals a shaft 60 to which the rocker arm 28 is keyed and whichrotatably supports an intermediately pivoted, double-ended, adjustablestop member El. A compression spring 62, Fig. 2, interposed between thearm 58 and a lower arm portion 6|a of the stop member 6| is guided by abolt 64 which passes sprawe freeiy through alignerlz openingsV inthe arm88 and' the arm portion 8|a,,a' nut dla being threaded on the inner endportion ofthebolt. Thevspring 52: biasesthe member 8 I' clockwise'aboutthe shaft 58 thereby forcing' an upper arm portion 81h of the member 64against a flat surface 85 of the contact supporting' rocker arm 28. Apin 88 extends outwardly from the portion Glb, passes freely through anopening in the arm 28, and mounts a compression spring 88 disposedbetween the arm 28 and an adjustment nut 68 threaded, on the outer endportion of the pin. By means of'the construction just described thecontacts ll and' 15 engage and disengage by rolling' action and are heldin engaged position by adjustable spring pressure as is well known inthe art.

Movement of the contacts I'S to engaged position is effectedmagnetically by attractive force between a magnet coreV 10, mounting" anOperating winding or coil ll, and a laminated magnetic armature 12resiliently mounted. as by spring structures 'll on the magnet arm 59.In the embodiment shown.. the core 10 is laminated, has shading coils15, and is secured to the base as by angle brackets 18. The coil 1| isprovided with suitable terminal leads 18.

The magnet arm 59 has an upwardly extending portion 58b (Figs. 4 and 6)which, when the coi11| is de-energized, abuts against a stop plate 18secured to and spaced from the, base |0 by a pair of elongated studs 8|.The blowout coil 20 may be of any type having suflicient turns to createan adequate blowout force, but, in order to have as low an inductance aspossible, should not have an excessive number of turns. As shown,insulated round Wire is used for the blowout coil and is form wound in adouble layer before being slipped over the core 2|, insulating discs orwashers 84 being pro- Vided at opposite ends of the coil. The magneticears 22 are pivotally supported on a screw 85 passing through atriangular insulator 86 mounted on the outer end portion of the bracket35 at the rear of the contact. ll'.

While the plate |8 may be a unitary piece of conducting metal, itpreferably has a lower por- .tion i8b of insulating material extendingover the major portion of the length of the plate, but

terminating to leave the conducting end portion contact.

Opposing marginal side portions of the plate l8 are received in grooves88 formed in the inner wall surface of the respective arc shield members34. The are shield members may be of molded insulation material andareheld together by the pin 31a to which the inner ends of the arcguiding conductor 32 are secured. Projections 88 formed beneath thegrooves 88 on the respective members' 3| meet beneath the plate 8 to.space the members 34 apart and to assist in the support of the plate. I

Ef more positive. means than the thermal effect of the arc itself isdesired for eifecting transfer of the arc from the contact to the plate|8, the non-electrical and non-magnetic arc transfer assisting meanscomprising the bellows 48 and nozzles 50 may be used. The bellows 48comprises a fiexible plunger 80 (Fig. 6) mounted within a cylindricalcontainer 8| which is fastened to the stop plate 18 as by a pair ofscrews: 821. A plunger actuating rod 84 secured to the base wall 88a ofthe plunger passes through aligned opening 95, 86 and 98 in a front wall8|b'of thecontainer, in the stop plate 78, and in an S-shaped bracket98, respectively. The bracket 88 is secured to the extension 59b of themagnet arm 58. When the magnet arm 59 moves to the closed position(shown in Fig. 6) the plunger 80 is compressed as a result of thepulling force on the rod 88 exerted by the braci-:et 88 against a nut588 threaded on the end of the rod, air inside the plunger beingdischarged througha port. 9M in the wall 8lb. When the magnet armreturns to the open position, the plunger restores itself to its normalcondition and forces air from the cylinder 8| through an outlet portE82' to a distributor lee. Because of the lost motion connection betweenthe rod 84 and, the bracket 89, the magnet arm 59 reaches its open'position without interference from the red.

Air entering the distributor HM flows through the pair of outletconduits 5d to the nozzles 5b of the two poles il and 12, respectively.The air is emitted from the nozzles through the orifices 49 concurrentlywith the formation of an are between the contacts H and IS. This puif ofair assists the thermal effect of the arc and positively drives the arcupwardly so that the outer end thereof transfers from the. contact flrtothe plate E8.

Referring to Fig. '7, the arc transfer may be effected by utilizing theforce of repulsion between two adjacent currents fiowing in oppositedirections, as mentioned. For this purpose a flexible conductor ll0,preferably uninsulated, comparabie to the conductor 26, andinterconnecting a terminal block HI and the movable contact M2 isconnected directly to the contact M3 through an elongated terminal tubeor member l l3. The member Il3 is disposed beneath and in fairly closeproximity to the are during the initial period of arc formation. Thecurrent in the are at any given instant is fiowing oppositely from thecurrent in the member M3 and theiforce of repulsion between these twocurrents forces the arc upwardly and facilitates its transfer to theplate IM, comparable to the plate 88 heretofore described.

The fiexible conductor M0 is provided at its lower end with a terminaltube or member M5 electrically connected to the terminal' block iii andhaving its end portion bent at right angles to the portion adjacent theconductor M0; The upper end of the conductor ilu is received in theelongated terminal member M3 which is electrically connected to themovable contact M2 as by being clamped between the contact M2 and arocker arm M8. The terminalimember M3 is preferably in the form of afiattened hollow copper tube bent as indicated and extends rearwardlyfrom the lower surface of the contact M2 toward an insulating base ll'l. The member M3 is of sufficient length so that it is disposed underthe entire path of the initial arc drawn when the contact M2 moves fromthe solid line position to the open position shown by broken lines M8. 1referably heat resisting insulation M8, such as glass tape impregnatedwith a silicone resin, be provided for the terminal member ll3.

When the movable contact M2 leaves the stationary contact l20, thecurrent through the contactor flows from the stud E2! through thebracket 122, the contact l20, the are, the contact III, the terminalmember I Il, the fiexibie conductor HO and through the terminal member5, to the terminal block Ill. It is thus seen that the current in thearc is flowing in a direction opposite to the current in the member Ill.The force of repulsion between these two oppositely flowlng currentsforces the arc upwardly and assists the inherent thermal effect of theheated are to cause the outer end of the arc to transfer from thecontact ||2 to the plate ill, thus initiating energization of theblowout coil 123 which is the same as the blowout coil 20, and isconnected in the contactor circuit in the same manner as the coil 20.The contactor of Pig. 7 is the same as that of Figs. 1 through 6 exceptthat, instead of 'the air-blast producing means for initiating movementof the arc to the plate |8, the flexible conductor lu has beenrearranged so as to perform this function, thus making possible moreeffective movement of the arc and simplification of the structure.

This application is a continuation-in-part of Iny copending applicationSerial No. 602,194, filed une 29, 1945, and entitled Electric Switches."now abandoned.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

I therefore particularly point out and distinctly claim as my invention:

i. A switch for opening and closing an electric oircuit comprising apair of relatively separable contacts operative upon separation to forma gap between the contacts across which a current can normally flow asan arc, a conductor connected 'to one of said contacts and adapted forconnection to one side of a circuit, the other of said contacts beingadapted for connection to the other side of the circuit, an are'terminal receiving means adjacent to said contacts, a hlowout coilconnected between said arc terminal receiving means and said one of saidcontacts, and said conductor having a portion positioned relative to thegap between said contacts so as to conduct the circuit current past asufiicient portion of the length of the gap, in adirection opposite toany are current between the contacts, at such proxirnity 'to the gapthat the said current flowing through said conductor moves a terminal ofthe arc toward said arc terminal receiving means.

2. A switch for opening and closing an electric circuit comprising astationary contact, a movable contact engageable with said stationarycontact and sepai'abie therefrom to form a gap between the contactsacross which a current can flow as an arc, a conductor connected to saidmovable contact and adapted for connection to one side of a circuit, thestationary contact being adapted for connection to the other side of thecircuit, an arc 'terminal receiving means adjacent said movable contact,a blowout coil connected between said arc terminal receiving means andsaid movable contact, and said conductor having a portion positionedrelative to the gap between said contacts so as to conduct the circuitcurrent past a suhstantial portion of the gap, in a direction oppcsiteto any arc current between the contacts, such proximity to the gap thatthe said current iiowing 'through said conductor moves a terminal of'the arc on the movable contact toward said arc terminal receivingmeans.

3. A switch according to claim 2 further char- ````acterized in thatmeans are provided for con- 0 straining to said position at least aportion of the conductor which is connected to the movable contact whileleaving the movable contact unconstrained by the said means andconductor in its movement in the opening direction.

4. A switch according to claim 2 further characterized in that theconductor which is connected to the movable contact is fiexible andmeans are provided for constraining at least a portion of said conductorto said position during the existence of said gap.

5. A switch according to claim 2 further characterized in that theconductor extends entirely across said gap when the contacts are intheir fully separated positions.

6. A switch according to claim 2 further characterized in that saidconductor has a rigid conducting portion connected to the movablecontact so as to be moved thereby to, and supported thereby in, said`position.

7. A switch for opening and closing an electric circuit comprising apair of relatively separable contacts operative upon separation to forma gap between the contacts across which a current can normally flow asan arc, a terminal adapted to be connected to one side of said circuit,a conductor means connected between one of said contacts and saidterminal, the other of said contacts being adapted for connection to theother side of the circuit, an are terminal receiving means adiacent tosaid contacts, a blowout coli, additional conductors connecting the coiibetween said arc terminal receiving means and said one contact, saidconductor means having a portion positioned relative to the gap betweensaid contacts so as to conduct the circuit current past the gap in adirection opposite to any arc current between the contacts at suchproximity to the gap that the said current flowing through saidconductor moves a terminal of the arc toward said arc terminal receivingmeans so as to reposition one of the are terminala thereon, whereby saidconductors and blowout coil are energized through the repositioned arc,and said conductors being positioned so as to divide and conduct anycurrent from the arc terminal receiving means past the repositioned arcin separate paths at opposite sides of the path of the repositioned arcin a direction opposite to the current of 'the repositioned arc suchproximity thereto that the current flowing through said conductorsconstrains the 'repositioned are from lateral displacement.

8. A switch in accordance with claim 1 characterized in that said arcterminal receiving means is disposed above said contacts in the the rmal path of movement of the arc and in that said conductor is positionedbelow the gap so as to urge the arc upward to augment the thermal effectof the are.

9. An e'iectromagnetic contactor for repeatedly opening and closing acircuit carrying an alternating current, said contactor comprising apair of terminals, a circuit of low inductance extending through saidcontactor from one of said terminals to the other and including an upperpor- 'tion and a lower portion which is disposed directly beneath and inclose proximity to at least a substantiai part of said upper portion,said upper and said lower portions defining opposing sides of the onlyloop in said circuit, a pair of separable contacts in said substantialpart of said upper portion which when closed carry all asiasae ll of thecurrent passing through said contaetor from one of said terminala to theother of said terminals and which upon separation while current isflowing therethrough draw an arc therebetween, said contacts being sodisposed that said arc upon its 'initiation extends substantially in ahorizontal plane at such proximity to said lower portion that thethermal effect of said arc and the. force of repulsion between thecurrent in said lower portion and the arc current conjointly 10 cause aterminal of said arc to move upwardly along one of said contacts, an arcreceiving means having an arc receiving surface elosely adjacent theupper portion of said one of said contacts and in the path of saidupward movement of said terminal of said arc, an electrical connectionbetween' said surface and the terminal to which said one contact ispermanently connected, a blowout coil in said connection and of such lowinductance that continued upward movement of said terminal of said arccauses said terminal of said arc to transfer from said one contact tosaid surface thereby to ener'gize said blowout coil. and the iluxproduced by said blowout coil being so direeted that said arc is forcedin the upward direction by said flux after said transfer.

10. A switch in aecordance with claim 1 characterized in that the saidportion of the conductor extends across the entire width of the gap inall positions of the contacts.

HILTON W. 63m8.

REFEBENCES CI'I'ED The following references are of record in the flle ofthis patent:

UNITED STATES PATEN'I'S

